1. Field of the Invention
The present invention relates to communications systems, and in particular, to systems communicating to or from vehicles using modulated electromagnetic radiation in the visible, infrared or other nearby spectra.
2. Description of Related Art
Driving a motor vehicle involves sending and receiving messages and signals of various types. Stoplights, flashing warning lights, detour signs and the like give the driver immediate driving information and instructions. Brake lights and turn signals are illuminated to alert nearby drivers of actions that are being taken or are about to be taken by a driver.
Brake lights and turn signals on many motor vehicles are implemented as LED arrays. Referring to FIG. 1 a schematic representation of an LED array 12 and power supply 18 are illustrated. LED array 12 is connected to the positive potential +V of supply 18 and ground. LED array 12 is an array of serially connected LEDs connected anode to cathode. The positive potential of supply 18 connects to the anode of the first LED of array 12 while the last one has its cathode connected to ground. The LEDs 12 are arranged to provide a voltage drop across the entire LED array 12 equal to the system voltage of the application in which the LED array 12 is installed. In typical vehicle applications the system voltage is commonly 6, 12, 24, or 50 volts. When the proper voltage is applied to the LED array 12, it will illuminate. LED arrays such as this are used in automotive applications typically for marker, brake, and turn signal lamps.
The information that can be conveyed by these traffic signals and vehicle signals is relatively limited. On the one hand, the media is limited to the visual. Also, the information content is relatively small and the sender does not have the opportunity to send more complicated messages.
In some cases a driver may want to receive more complex information. For example, if a detour is necessary the driver may want to know more about the appropriate detour route. If traffic congestion lies ahead, a driver would like to know about such difficulties in advance and receive sufficient information to plot a course avoiding such congestion. The driver may use a radio to get traffic reports, but these are often not comprehensive and current, are not available continuously, and may report only the most serious congestion.
Drivers can receive information from various wireless devices such as cell phones, wirelessly connected PDAs, CB radios, walkie-talkies, etc. These devices are not however well adapted to provide information about the driver's immediate surroundings. Also, such devices may require a driver to operate a keyboard or control panel, which may not be feasible or safe while driving.
See also, U.S. Pat. Nos. 3,601,792; 3,604,805; 3,790,780; 3,941,201; 4,670,845; 5,295,551; 5,568,136; 5,635,920; 5,708,415; 5,736,935; 5,914,652; 5,986,575; 6,243,026; 6,369,720; 6,654,681; 6,850,170; 6,885,282; and 6,943,677.